Information descriptor and extended information descriptor data structures for digital television signals

ABSTRACT

According to an aspect, there is provided a digital television (DTV) data stream including program and system information protocol (PSIP) data associated with content of the DTV data stream, the PSIP data including a virtual channel table (VCT) and an event information table (EIT), the EIT comprising: a source identification field identifying a source of an associated event in a DTV data stream; an event identification field indicating an identification of the event; a start time field indicating a star time of the event; a title field indicating a title of the event; and a descriptor comprising: a descriptor tag identifying the descriptor as a genre descriptor, a descriptor length indicating a total length of the descriptor; and at least one category code for an associated event in a DTV data stream, each category code specifying genre, program type, or category information of the associated event, wherein the at least one category code specifies at least one of a set of basic categories.

CONTINUITY DATA

This application is a continuation of co-pending application Ser. No.14/242,606, filed on Apr. 1, 2014 which is a continuation of applicationSer. No. 13/610,346, filed on Sep. 11, 2012 (now issued as U.S. Pat. No.8,782,705) which is a continuation of application Ser. No. 13/032,265,filed on Feb. 22, 2011 (now issued as U.S. Pat. No. 8,510,777) which isa continuation of application Ser. No. 11/980,820, filed on Oct. 31,2007 (now issued as U.S. Pat. No. 7,917,926) which is a continuation ofapplication Ser. No. 11/211,541, filed on Aug. 26, 2005 (now issued asU.S. Pat. No. 7,877,770) which is a continuation of application Ser. No.09/835,559, filed on Apr. 17, 2001 (now issued as U.S. Pat. No.7,877,769), the entire contents of which are hereby incorporated byreference and for which priority is claims under 35 U.S.C. §120. Thisapplication claims priority upon U.S. Provisional Patent Application No.60/197,676, filed Apr. 17, 2000, the entirety of which is herebyincorporated by reference.

FIELD OF THE INVENTION

The invention is directed to meta data for use in digital televisionsignals, and more particularly for meta data in a digital televisionsignal that is used to generate an electronic program guide.

BACKGROUND OF THE INVENTION

An electronic program guide (EPG) is a (typically) interactive graphicaluser interface (GUI) that a receiver of a digital television (DTV)signal can generate. An EPG is superimposed on the DTV event, e.g.,program, that is currently being displayed. The EPG provides aviewer/user with information about the events currently being shown andthat will be available for some amount of time into the future.

Some EPGs can only provide textual descriptions of the eventsthemselves, of the ratings of potentially-objectionable content in theevents (content advisory ratings) and of the encoding information.Encoding information can include indications of DOLBY stereo audio,which video format is used (e.g., there being 18 video formats accordingto the American Television Standards Committee standard for terrestrialdigital television), closed captioning availability, etc. Examples ofsuch EPGs are depicted in FIGS. 1-2.

A specific type of DTV signal is a terrestrial broadcast DTV signal thatconforms to the standards of the Advanced Television Standards Committee(ATSC). Among the many ATSC standards for aspects of a terrestrial DTVsignal, the specification for meta data used in an EPG is contained inATSC A/65 and its addenda, A/66 and A/67. Such meta data is referred toas Program and System Information Protocol (PSIP) data. The PSIPspecification promulgated by the ATSC only provides for textualdescriptions of the events themselves, of the ratings ofpotentially-objectionable content in the events and of the encodinginformation. As such, the current PSIP specification only provides foran EPG that is about as visually-compelling as those of FIGS. 1-2, Inother words, the current PSIP-specified EPG is not visually compelling,i.e., it is bland in appearance.

Given the great improvement in the quality of event images made possibleby an ATSC-compliant terrestrial DTV signal, such a bland EPG isinconsistent. Broadcasters and content providers want to add moreviewer-compelling advertising and event-content information to the EPGdisplays. It is a problem that there is no standard way of providingsuch advertising and event-content information.

SUMMARY OF THE INVENTION

The invention, among other things, provides a solution to the problemdescribed above.

The invention, in part, provides, a new type of meta data structure thatprovides data and/or or a link to such data that is used by an EPGgenerator in a DTV receiver to display visually-compelling informationabout an event. Such information can include: an icon associated withthe broadcaster of the event and/or the source of the event; a graphicrepresenting a rating of potentially-objectionable content in the event;a still image representative of or having a relation to the event; avideo excerpt of or having a relation to the event; an advertisementrelated to the event, its broadcaster and/or its source; etc.

The invention, also in part, provides a meta data structure (adescriptor) that can be attached to entries in PSIP tables, e.g., anevent in an event information table (EIT) or a virtual channel in avirtual channel table (VCT). The descriptor provides a way to referenceother content in a different or the same DTV data stream or availablevia a network that can be used by the receiver to display other types ofcontent. The descriptor also provides the type of the data and anexpected usage of the data.

Parsing and displaying the visually-compelling information provided viasuch a descriptor is an optional feature of a DTV receiver system. Forthose that support this mechanism, the EPG that a DTV receiver generatescan be enhanced dramatically.

The meta data structure (descriptor) according to the invention isespecially advantageous because of the typing and usage values that itcontains. A DTV receive can analyze such typing and usage values beforeaccessing the data referenced in the descriptor. In some instances, suchpre-access analysis can preclude the EPG generator from attempting togenerate the visually-compelling information, thus reducingcomputational overhead and computing resource waste.

According to an aspect of the present invention, there is provided adigital television (DTV) data stream including program and systeminformation protocol (PSIP) data associated with content of the DTV datastream, the PSIP data including a virtual channel table (VCT) and anevent information table (EIT), the EIT comprising: a sourceidentification field identifying a source of an associated event in aDTV data stream; an event identification field indicating anidentification of the event; a start time field indicating a star timeof the event; a title field indicating a title of the event; and adescriptor comprising: a descriptor tag identifying the descriptor as agenre descriptor; a descriptor length indicating a total length of thedescriptor, and at least one category code for an associated event in aDTV data stream, each category code specifying genre, program type, orcategory information of the associated event, wherein the at least onecategory code specifies at least one of a set of basic categories.

According to another aspect of the present invention, there is provideda memory for containing program and system information protocol (PSIP)data associated with content of a digital television (DTV) data stream,the PSIP data including a virtual channel table (VCT) and an eventinformation table (EIT), the EIT comprising: a source identificationfield identifying a source of an associated event in a DTV data stream;an event identification field indicating an identification of the event;a start time field indicating a star time of the event; a title fieldindicating a title of the event; and a descriptor comprising: adescriptor tag identifying the descriptor as a genre descriptor; adescriptor length indicating a total length of the descriptor; and atleast one category code for an associated event in a DTV data stream,each category code specifying genre, program type, or categoryinformation of the associated event, wherein the at least one categorycode specifies at least one of a set of basic categories.

Advantages of the present invention will become more apparent from thedetailed description given hereinafter. However, it should be understoodthat the detailed description and specific examples, while indicatingpreferred embodiments of the invention, are given by way of illustrationonly, since various changes and modifications within the spirit andscope of the invention will become apparent to those skilled in the artfrom this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description given hereinbelow and the accompanying drawingswhich are given by way of illustration only, and thus do not limit thepresent invention.

FIGS. 1-2 are depictions of visually-bland EPG screens according to thebackground art.

And FIG. 3 is a depiction of an EPG screen that includesvisually-compelling information made available by way of one or more ofthe meta data structures according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Examples of four meta data structures (descriptors) according to theinvention will be described. Such descriptors extend the sort ofinformation that can be supplied in a digital television (DTV) signalthat complies with the program and system information protocol (PSIP)meta data specification promulgated for digital terrestrial televisionaccording to the Advanced Television Standards Committee (ATSC). Suchextended information makes it possible for a ATSC-compliant receiver togenerate an electronic program guide (EPG) the includesvisually-compelling information.

FIG. 3 is a depiction of an example of an EPG screen 300 that includes,among other pieces of information, visually-compelling information madeavailable by way of one or more of the meta data structures according tothe invention. The EPG screen 300 includes a grid 302 that represents atleast a portion of the schedule of events that a DTV receiver canreceive. The grid 302 has rows representing each broadcast channel. Forsome of the rows, a visually-compelling logo graphic associated with theDTV broadcaster of the respective channel, such as graphic 304A, 304B,304C and 304D, is depicted.

One of the events, 306, in one of the rows is depicted slightlydifferently (boxed) to denote its selection by a user of the EPG. Due toits selection, additional visually-compelling information about theevent, here the movie “BLUES BROTHERS,'” is depicted. This additionalinformation includes the following: logo graphic 308 associated with theDTV broadcaster of the respective channel; a graphic 310 representing arating of potentially-objectionable content in the event; and a movieexcerpt still image 312 from the event.

The EPG screen 300 also includes an advertisement graphic 314 related insome way to the selected event 306, the broadcaster of the selectedevent 314 and/or the source of the selected event 314. Here, theadvertisement 314 is for a competing broadcaster of movies etc, that haspaid to linked in the EPG meta data so as to be displayed whenever amovie is selected by a user.

The logo graphics 304A-D and 308, the rating graphic 310, the movieexcerpt image 312 and the advertisement 314 can each be a still ordynamic image of any suitable image format, such as any one of aGIF-formatted image file, a JPEG-formatted image file, a TIFF-formattedimage file, an ASCII text file, an HTML-formatted text file, anXML-formatted text file, a basic audio formatted file having a .au fileextension, an MPEG-formatted audio file, a WAV-formatted audio file, anMPEG-formatted video file, a Quicktime-formatted video file, anAVI-formatted video file, a user-defined formatted file, etc.

The logo graphic 308 can be the same as logo graphic 304A or it can bedifferent. Also, it is not necessary to include all of thevisually-compelling pieces of information 304A-D, 308, 310, 312 and 314in an EPG screen.

A meta data generator that can easily be adapted to generate thedescriptors according to the invention is the PSIP BUILDER PRO brand ofPSIP generator manufactured and sold by TRIVENI DIGITAL INC. The PSIPBUILDER PRO itself is based upon a programmed PC having a Pentium typeof processor using the MICROSOFT WINDOWS NT4.0 operating system, withthe application software being written in the Java language.

Known text-based EPGs, such as that made and sold by the SHARPCorporation or the RCA Corporation (e.g., model no DTC100), can easilybe adapted to recognize and operate upon the descriptors according tothe invention.

The first example descriptor according to the invention describes typesof visually-compelling data associated with an event not defined. Someof the types of such data might not be described in the PSIPspecification.

The other example descriptor according to the invention describes wherethe visually-compelling data described by the first example descriptorcan be found by the electronic program guide (EPG) generator of the DTVreceiver.

The example descriptors according to the invention can be included inVirtual Channel Tables (VCTs) and Event Information Tables (EITs). Thisallows the broadcaster to include a broad range of informational dataassociated with a virtual channel or an event, respectively.

A brief review of EITs and VCT's according to the PSIP specification isnow provided. Generally, an EIT identifies: events, e.g., units ofprogramming, the titles of the events; the start times of the events;and the durations of the events. There may be up to 128 EITs, designatedEIT-0 through EIT-127, each covering a three hour period. There amultiple instances of EITs for any given three hour period, i.e., oneEIT for each virtual channel. A VCT identifies and describes virtualchannels in a physical channel allotted to a terrestrial DIVbroadcaster.

The known EIT has the table identification (id) 0xCB and can include thefollowing for each event (referred to as being in the particular event'sloop) in its three hour period: a source id field (that points to thesource of the physical channel containing the virtual channel in whichthe event can be found); an event id field; a start time field; anextended text message (ETM) location flag; a length field in units ofseconds; a title field; a captions service descriptor field; a contentadvisory descriptor field; and other descriptor fields as yetunspecified by the PSIP.

The first and/or second example descriptors according to the inventioncan occupy one or more of the as yet unspecified descriptor fields in anEIT.

The known VCT can be a terrestrial VCT (TVCT) or a cable VCT (CVCT). Itcan have the table id 0xC8 (TVCT) or 0XC9 (CVCT) and include a transportstream id field that identifies the physical channel allotted to theterrestrial DTV broadcaster. For each virtual channel in the physicalchannel, the known VCT, among other things, includes: a short channelname field; a major channel number field (often corresponding to theanalog television channel number previously associated with thebroadcaster); a minor channel number field; a modulation mode field; acarrier frequency mode field; a channel transport stream id fieldrepresenting the frequency band of the physical channel consumed by thevirtual channel; an extended text message (ETM) location flag; a servicetype indication field; a source id field (that defines a unique numberthat can be used to identify the virtual channel within the transportstream multiplex); a service location descriptor field; and otherdescriptor fields as yet unspecified by the PSIP.

The first, second and/or third example descriptors according to theinvention can occupy one or more of the as-yet-unspecified descriptorfields in a VCT. The third example descriptor should be included in oneor more of the as-yet-unspecified descriptor fields in an EIT.

The first descriptor provides information for associating a type of datawith one of the known multipurpose internet mail extensions (MIMEs).This allows a DTV receiver of the descriptor to create a table of typesof such data.

The second descriptor is a uniform resource locator (URL) referenceproviding information about (or a link to) where to find the specificdata resource. Such a URL can typically describe the type of accessmethod being used (http) and/or the server location or data streamhaving the specific data resource.

The third example descriptor is an embellishment of the seconddescriptor in the sense that it adds indicators about the associatedcontent regarding; whether it is an advertisement; whether it should bedisplayed with or separately from an EPG screen; and/or where on adisplay screen it should be located.

The fourth example descriptor defines the genre of the information(event with which it is associated).

The first descriptor, also known as the Information Type Descriptor,will now be discussed in more detail.

The information type descriptor according to the invention is used todescribe data types not defined by the ATSC's PSIP standard. Asdescribed herein, some non-standard data types are predefined, but moregenerally the invention provides a way to define such non-standard datatypes.

The predefined data types correspond to those data types that aretypically understood by known receivers. The form of the descriptorfollows the standard descriptor form found in ISO/IEC 13818-1:1996,Information technology—Generic coding of moving pictures and associatedaudio information: Systems (normative).

The Information Type Descriptor syntax is defined in Table 1 as havingthe following fields.

TABLE 1 Bit Stream Syntax for the Information Type Descriptor SyntaxBits Format information_type_descriptor ( ) {   descriptor_tag 8 0xC9  descriptor_length 8 uimsbf (unsigned integer, most significant bitfirst)   information_type_id 8 uimsbf   information_desciption_length 8uimsbf   information_description_text var }

The field, descriptor_tag, is for an 8-bit unsigned integer. It shouldhave the value 0xC9. And it identifies the descriptor as theinformation_type_descriptor.

The field, descriptor_length, is for an 8-bit unsigned integer. Itspecifies the length (in bytes) of the fields immediately following thisfield through to the end of the information type descriptor.

The field, information_type_id, is for an 8-bit unsigned integer. Itspecifies the information type identifier being defined. Theinformation_type_id is a shorthand representation of the informationaltext in a field (information_description_text) that indirectly followsit. The expectation is that the decoder (in the DTV receiver) of theinformation can save this identifier to associate it with theinformation description, allowing the extended information descriptor touse the id instead of the full description text.

Predefined examples of the information_type_id are described in Table 2.

TABLE 2 Predefined Information Type Identifiers ID Text Meaning 0x00image/gif A GIF-formatted image file 0x01 image/jpeg A JPEG-formattedimage file 0x02 image/tiff A TIFF-formatted image file 0x03image/x-xbitmap An XBM-formatted image file 0x04-0x07 Reserved 0x08text/plain A plain ascii text file 0x09 text/html An HTML-formatted textfile 0x0A text/xml An Xml-formatted text file 0x0B-0x0F Reserved 0x10audio/basic A basic audio file format (.au) 0x11 audio/x-mpeg AnMPEG-formatted audio file 0x12 audio/x-wav A WAV-formatted audio file0x13-0x17 Reserved 0x18 video/mpeg An MPEG-formatted video file 0x19video/quicktime A Quicktime-formatted video file 0x1A video/avi AnAVI-formatted video clip 0x1B-0x1F Reserved 0x20-0xff User Defined

Continuing with the discussion of the fields in the information typedescriptor, the field, information_description_length, is for an 8-bitunsigned integer. It specifies the length (in bytes) of the informationdescription that immediately follows. This value is equal todescriptor_length—2 bytes.

The field, information_description_text, is for the description of theinformation. Typically, this can be a textual MIME type. For example,‘image/gif’ can be used to specify that the information_type_idcorresponds to the GIF image file type. This field can contain any valuethat can be interpreted by the decoder.

The second descriptor, also known as the Extended InformationDescriptor, will now be discussed in more detail.

The extended information descriptor can contain three fields: a typeidentifier field that indicates the type of the data being referenced;an expected usage field; and a URL field indicating where theinformation can be found. The type identifier field can refer to thefirst example descriptor according to the invention.

The extended information descriptor makes it possible for data to besupplied either in a program included in a transport stream (using thedigital storage media command and control (DSMCC) protocol described inISO/IEC 13818-6 (1998) or some other data protocol) or from some othersource (the world wide web, the internet, a private network, etc.). Theform of the descriptor follows the standard descriptor form found in,again, ISO/TEC 13818-1:1996, Information technology—Generic coding ofmoving pictures and associated audio information: Systems (normative).

The Extended Information descriptor syntax is defined in Table 3.

TABLE 3 Bit Stream Syntax for the Extended Information Descriptor SyntaxBits Format extended_information_descriptor ( ) {   descriptor_tag 80xC8   descriptor_length 8 uimsbf   information_type_id 8 uimsbf  information_expected_usage 8 uimsbf   information_location_length 8uimsbf   information_location_text Var }

The field, descriptor_tag, is an 8-bit unsigned integer. It should havethe value 0xC8. And it identifies the descriptor as theextended_information_descriptor.

The field, descriptor_length, is for an 8-bit unsigned integer. Itspecifies the length (in bytes) of the fields immediately following thisfield through and to the end of the extended information descriptor.

The field, information_type_id, is for an 8-bit unsigned integer. Itspecifies the type of information that resides at the specifiedlocation.

The field, information_expected_usage, is for an 8-bit unsigned integer.It specifies the expected or intended usage of the informationreferenced by this descriptor. Table 4 defines some settings for thisfield. The expected usage indicates a hint to the receiver as to whereand/or how the information's creator intended the information to bedisplayed. Some receivers might not be able to comply with this hint.Behavior in these instances is not defined, but is left to theparticular operability of the receiver.

TABLE 4 Information Expected Usage Definitions Value Bits 0x00Undefined - No expected usage. Display when and where convenientdepending on type. 0x01 Extended Event EPG Information (Displayed duringEPG display when event is selected). 0x02 Extended Event SelectedInformation (Displayed when event is selected). 0x03-0x0F Reserved forfuture Event Usage definitions. 0x10 Extended Channel EPG Information(Displayed during EPG display when channel is selected). 0x11 ExtendedChannel Selected Information (Displayed when the channel is selected).0x12-0x1F Reserved for future Channel Usage definitions. 0x20-0x7FReserved for future usage. 0x80-0xFE User defined. 0xFF Reserved.

Continuing with the discussion of the fields in the extended informationdescriptor, the field, information_location_length—This 8-bit unsignedinteger specifies the length (in bytes) of the location text immediatelyfollowing this field to the end of the descriptor. This field is equalto the descriptor_length—2.

The field, information_location_text—This data represents a string ofcharacters that is interpreted as a URL. The URL is used to referenceeither a particular data program (e.g., dtv:/salesdata.com) or someother data from, e.g., the www (e.g.,http://www.weatherchannel.com/images/logo.gif) or a private network.

The extended information descriptor can be used to specify additionalinformation about a virtual channel or event in a DTV decoder system.This provides for multimedia or graphical elements that can be used toenhance the event or virtual channel data. For example, information in aVCT could refer to a banner advertisement or some graphic with a logoassociated with a broadcaster. The associated broadcaster would havesome relation (perhaps even that of a competing broadcaster) to that thebroadcaster to whom is assigned the physical channel in which thecurrently-highlighted/selected virtual channel is found. The DTV decoderwould then display that information in appropriate locations based oninteractions with the user.

The selection of such appropriate locations represents an aspect of thedecoder within a DTV receiver and is within the ordinary level of skillin the art. In FIG. 3, such a banner advertisement 314 is located at thetop portion of the EPG screen 300. The extended information descriptorfor banner advertisement 314 would indicate aninformation_expected_usage field value of 0x11.

Similarly, if the descriptor is included as part of the eventinformation, the DTV decoder can display extended information such asgraphics, ads or even video clips when the user asks for informationabout the event in the EPG or through some other interaction. Thedescriptor would indicate an information_expected_usage of 0x01 for thissituation.

The extended information descriptor is intended to be a simple referenceto the actual data. Since the descriptor includes a URL, the data may belocated anywhere and can be displayed if it is accessible by thereceiver. The receiver should be very flexible in changing displays ifthe resource cannot be accessed. Again, this an aspect of the decoderwithin a DTV receiver that is within the ordinary level of skill in theart.

For many broadcasters, it will be advantageous to provide theseresources carrouseled in a separate program stream within theirbroadcast stream, thus allowing the receiver to quickly obtain theinformation and display it if the receiver can format the particularfile type.

Again, the Information Type descriptor allows the user to extend thetypes of data that can be sent. The descriptor allows the encoder tospecify which identifiers map to which types of data. In this way, adecoder can leverage off previous standards, specifically the MIME typestandards, to determine how a data set should be interpreted. TheInformation Type descriptor is a definition mechanism to allow theencoder to indicate which id will be used for a given MIME type.

For an overall example, assume that a broadcaster KXYZ has a number ofbanner ads that are being used on the broadcaster's web site to identifythe three virtual DTV channels that the broadcaster is providing in theDTV domain via its allotted physical terrestrial DTV channel. Thebroadcaster also uses a listing service that supplies informationconcerning the programming along with advertising for those programs.The listing data takes the form of a database that is converted intoATSC A/65-compliant PSIP data. In addition to the program textualinformation, the listing service also provides a number of pictures(graphics files) that are stills of the respective programs.

To provide a visually-compelling EPG screen as well as advertising tothe customer/viewer/user of the EPG, the broadcaster in the overallexample decides to include the graphical information concerning thechannels provided along with program graphics. The broadcaster uses aportion of the broadcast stream to supply the graphics files in a datacarrousel. This carrousel is encoded as program 16. Thus, the programmap table (PMT) of the program is encoded at packet identifier (PID)0x0100. The carrousel is placed on PID 0x010A according the ATSC programinformation guidelines (A/53). The URL(s) associated with this datacarrousel are supplied as part of the PSIP information in the data eventtables (DETs) (which were previously referred to as DITs).

In the overall example, the URL of each of the data elements isidentified as “btv://kxyz16.kxyz.com/images/progImage.gif” where‘progImage.gif’ represents one of the files being provided for each ofthe programs and “btv” denotes broadcast television. Such a URL isdescribed in more detail in commonly assigned copending application Ser.No. 09/188,189, filed Nov. 10, 1998, the entire contents of which arehereby incorporated by reference.

Assuming the listing service does not supply a complete set of stills,the broadcaster could merely include those that are most important. Inaddition, the broadcaster can also supply the images from the web sitethat are used as banners. These are referenced as“btv://kxyz16.kxyz.com/images/bannerX.gif” where “bannerX.gif”represents the banner for each channel X. The carrousel is sent at alimited rate based on the broadcaster's available bandwidth.

For the overall example, in the descriptor loop of each virtual channel(see ATSC A/65 Section 6.3), the extended information descriptor isadded which references the banner file supplied. Thus, the descriptorcan have the values shown in Table 5.

TABLE 5 Extended Information Descriptor for Virtual Channel 1 SyntaxValue Explanation extended_information _descriptor ( ) {  descriptor_tag 0xC8   descriptor_length 42 The total byte count.  information_type_id  0 Indicating a gif file.  information_expected_usage 0x10 Display during Channel EPG display.  information_location_length 40 The total character count in the text.  information_location_text ‘btv://kxyz16.kxyz.com/ The URL of the firstimages/banner1.gif’ banner for the first channel. }

In Table 5, it is noted that the information_type_id takes advantage ofthe predefined types of files to indicate that the file is a GIF.Similarly, the reference to each program event extended information isencoded in the associated EITs as in Table 6.

TABLE 6 Example Extended Information Descriptor for Event n Syntax ValueExplanation extended_information _descriptor ( ) {   descriptor_tag 0xC8  descriptor_length 44 The total byte count.   information_type_id  0Indicating a gif file.   information_expected_usage 0x01 Display duringEvent EPG display.   information_location_length 42 + digits The totalcharacter count in the text. for N   information_location_text‘btv://kxyz16.kxyz.com/ The UI of the gif image associatedimages/progImageN.gif’ with event N. }

In the overall example, the data need only be sent as frequently as thetable it is associated with. Accordingly, the carrousel algorithms canbe tuned to only send the channel extended information as fast as theVCT while the event information need only be delivered as fast as theEIT referencing the data. Similarly, when an EIT or Virtual channelbecomes obsolete, the associated extended information can be removedfrom the broadcast stream.

The third descriptor, also known as the External Extended InformationDescriptor, will now be described in more detail. The third descriptorincludes: a type identifier that indicates the type of the datareferenced; a group of hints about usage and positioning (on an EPG suchas that of FIG. 3); a start time when the data is valid for display; aduration indicating how long the data should be used; and a URLindicating where the information may be found.

The data for this specific demonstration can be contained in privatetables within the same transport stream. The URL referencing this datacan take the form “ptm:/<path>” or “ptd:/<extendedID>”. The form of thedescriptor follows the standard descriptor form found in ref. [2]. Thedescriptor tag can be defined as 0xC8 for the extended informationdescriptor.

While there are specific fields providing for usage hints, the actualplacement of the descriptor in either the EIT event descriptor loop orVCT virtual channel descriptor loop provides a way to associate theextended information with an event or with a virtual channel. Includingthis information in the descriptor (as in previous specifications) isredundant. The Extended Information descriptor syntax is defined inTable 7.

TABLE 7 Bit Stream Syntax for the Extended Information Descriptor SyntaxBits Format extended_information_descriptor ( ) {   descriptor_tag 80xC8   descriptor_length 8 uimsbf   information_type_id 8 uimsbf  information_advertisement_hint 1 bslbf   information_guide_hint 1bslbf   information_position_hint 3 uimsbf   information_size_hint 3uimsbf   information_start_time 32 uimsbf   information_duration 32uimsbf   information_location_text var }

The fields, descriptor_tag, and descriptor_length, have been describedabove.

The field, information_advertisement_hint can be a single bit indicatingwhether the associated information represents an advertisement or not.Advertisement information is indicated with a value of ‘1’ while otherinformation is indicated with a value of ‘0’. Advertisement informationwill usually be information that is not directly associated with theparticular service or event.

The field, information_guide_hint can be a single bit indicating thatthe information is intended to be displayed during Program Guide mode orduring regular program display. A value of ‘1’ indicates that theinformation is better displayed on program guide. A value of ‘0’indicates that the information is better displayed on the programdisplay.

The field, information_position_hint can be 3 bits that indicate a hintas to the best position for the particular information. Table 8 providessome example meanings for each of the values.

TABLE 8 Information Position Hint Values Value Meaning ‘000’ Undefined -No positional information supplied. ‘001’ Background - The associatedinformation should be used as a background of the display if possible.‘010’ Logo - Indicates that the information contains a logo that shouldbe displayed in appropriate positions. ‘011’ Reserved ‘100’ Upper LeftQuadrant (Position 1) ‘101’ Upper Right Quadrant (Position 2) ‘110’Lower Left Quadrant (Position 3) ‘111’ Lower Right Quadrant (Position 4)

The field, information_size_hint, can be 3 bits that indicate theintended size for the display of the referenced information. A value of‘000’ indicates that no size hint is defined for the referencedinformation. Values ‘001’ through ‘111’ indicates a range of small tolarge, respectively. The hint may be applied differently based on thetype of information. For example, small may indicate that a particulargraphic image be displayed in a smaller size while small may mean smallfonts for text information.

The field, information_start_time can be 32 bits representing anunsigned integer specifying the start time when the referenced data isvalid for display. The time can be represented in GPS seconds since 12am, Jan. 6, 1980 (standard GPS time). The receiver should not displaythe data until this time is reached. A value of zero indicates that thedata is valid whenever present, that is, there are no time constraints.

The field, information_duration—This 32 bits representing an unsignedinteger specifying the duration from the start time when the referenceddata is valid for display. The duration can be represented in seconds.The data should be displayed for the time frame specified by the starttime for the duration specified. A value of zero indicates that there isno time limit on the particular data element.

The field, information_location_text, can be a variable length string ofcharacters that is interpreted as a URL. The length of this field isequal to descriptor_length—10. The string can have a maximum of 245characters. Such a URL can take at least two forms: file reference andtable_id_extension reference. Protocol indicators can be used toindicate which form to apply. The indicator “ptm” stands for “PrivateTable Map” and can be followed by a text string that can be useddirectly to look up table_id_extension references in the mapping table.The indicator “ptd” stands for “Private Table Direct” and can befollowed by a number that will correspond directly to thetable_id_extension of the private table carrying the data file. ExampleURLs are “ptm:/demo/logo.gif” and “ptd:/27”. In the first case, thereceiver software can use the mapping table supplied in the data stream(PID 0x1ffa, Table ID 0xBD, table_id_extension 0x0000) to find out whichtable_id_extension corresponds to “demo/logo.gif”. The resultanttable_id_extension can be used to acquire the corresponding table (PID0x1ffa, Table ID 0xBD, table_id_extension n) and display the logo datafound in the table sections. In the second case, the receiver softwarecan use the value “27” directly to look up the private table in thestream (PID 0x1ffa, Table ID 0xBD, table_id_extension 0x001B).

The fourth descriptor, also known as the genre descriptor, will now bedescribed in more detail.

The genre descriptor contains a list of category selection codes. Thesecodes are defined in Table 6.25 of the A/65 Addendum. The fourthdescriptor can contain a list of any number of these category codes toallow the associated event to be filtered. The codes can be placed inthe descriptor in priority order, e.g., most generic to most specific.The descriptor tag can be 0xCA. The Genre descriptor syntax is definedin Table 9.

TABLE 9 Bit Stream Syntax for the Genre Descriptor Syntax Bits Formatgenre_descriptor ( ) {   descriptor_tag 8 0xCA   descriptor_length 8uimsbf   for (i==0; i<descriptor_length; i++) {    category_selection_code 8 uimsbf   } }

The field, descriptor_tag, can be an 8-bit unsigned integer having thevalue 0xCA, identifying the descriptor as the genre_descriptor.

The field, descriptor_length, has been described above.

The field, category_selection_code, can be an 8-bit unsigned integerspecifying a category selection code as defined in Table 6.25 of theA/65 Addendum. For example, the codes can be arranged from most genericto most specific. As a more specific example, a classic Western moviecan have a genre descriptor with the following content:

0xCA tag 0x03 length 0x22 “Movie” 0x89 “Classic Film” 0x7F “Western”

Selection codes are not normative but informative, so there are nomandatory codes only informational codes allowing the receiver to betterserve the consumer in finding specific content. Table 6.25 of the A/65Addendum is included below (as Table 10) for convenience.

TABLE 10 Table 6.25 of A/65 Addendum Categorical Selection CodeAssignments Value Meaning 0x00 Not Available 0x01-1F Reserved 0x20Education 0x21 Entertainment 0x22 Movie 0x23 News 0x24 Religious 0x25Sports 0x26 Other 0x27 Action 0x28 Advertisement 0x29 Animated 0x2AAnthology 0x2B Automobile 0x2C Awards 0x2D Baseball 0x2E Basketball 0x2FBulletin 0x30 Business 0x31 Classical 0x32 College 0x33 Combat 0x34Comedy 0x35 Commentary 0x36 Concert 0x37 Consumer 0x38 Contemporary 0x39Crime 0x3A Dance 0x3B Documentary 0x3C Drama 0x3D Elementary 0x3EErotica 0x3F Exercise 0x40 Fantasy 0x41 Farm 0x42 Fashion 0x43 Fiction0x44 Food 0x45 Football 0x46 Foreign 0x47 Fund Raiser 0x48 Game/Quiz0x49 Garden 0x4A Golf 0x4B Government 0x4C Health 0x4D High School 0x4EHistory 0x4F Hobby 0x50 Hockey 0x51 Home 0x52 Horror 0x53 Information0x54 Instruction 0x55 International 0x56 Interview 0x57 Language 0x58Legal 0x59 Live 0x5A Local 0x5B Math 0x5C Medical 0x5D Meeting 0x5EMilitary 0x5F Miniseries 0x60 Music 0x61 Mystery 0x62 National 0x63Nature 0x64 Police 0x65 Politics 0x66 Premier 0x67 Prerecorded 0x68Product 0x69 Professional 0x6A Public 0x6B Racing 0x6C Reading 0x6DRepair 0x6E Repeat 0x6F Review 0x70 Romance 0x71 Science 0x72 Series0x73 Service 0x74 Shopping 0x75 Soap Opera 0x76 Special 0x77 Suspense0x78 Talk 0x79 Technical 0x7A Tennis 0x7B Travel 0x7C Variety 0x7D Video0x7E Weather 0x7F Western 0x80 Art 0x81 Auto Racing 0x82 Aviation 0x83Biography 0x84 Boating 0x85 Bowling 0x86 Boxing 0x87 Cartoon 0x88Children 0x89 Classic Film 0x8A Community 0x8B Computers 0x8C CountryMusic 0x8D Court 0x8E Extreme Sports 0x8F Family 0x90 Financial 0x91Gymnastics 0x92 Headlines 0x93 Horse Racing 0x94 Hunting/Fishing/Outdoors 0x95 Independent 0x96 Jazz 0x97 Magazine 0x98 Motorcycle Racing0x99 Music/Film/Books 0x9A News-International 0x9B News-Local 0x9CNews-National 0x9D News-Regional 0x9E Olympics 0x9F Original 0xA0Performing Arts 0xA1 Pets/Animals 0xA2 Pop 0xA3 Rock & Roll 0xA4 ScienceFiction 0xA5 Self Improvement 0xA6 Sitcom 0xA7 Skating 0xA8 Skiing 0xA9Soccer 0xAA Track/Field 0xAB True 0xAC Volleyball 0xAD Wrestling 0xAE-EFReserved 0xF0-FE Reserved for expansion of Basic categories (e.g.0x20-0x26) 0xFF Null (not a category)

An overall example of the fourth example descriptor will be provided; itis entitled demo Mapping Table (dMT) and depicted in Table 11. It isassumed that this table can be cached on the STB so that it can betransmitted at a relatively low interval (e.g., 10 seconds). The dMT canbe updated every time a change is made to the data stream. Mappings canremain the same across versions of the table whenever possible.

TABLE 11 Bit Stream Syntax for demo Mapping Table (dMT) Syntax BitsFormat demo_mapping_table_section ( ) {   table_id 8 0xBD  section_syntax_indicator 1 ‘1’   private_indicator 1 ‘1’   reserved 2‘11’   section_length 12 uimsbf   table_id_extension 16 0x0000  reserved 2 ‘11’   version_number 5 uimsbf   current_next_indicator 1‘1’   section_number 8 uimsbf   last_section_number 8 uimsbf  mappings_defined 16 uimsbf   for (i=0;i<mappings_defined;i++) {    referenced_table_id_extension 16 uimsbf     reserved 3 ‘111’    referenced 5 uimsbf _table_version_number    information_location_length 8 uimsbf     for(j=0;j<information_location_length;j++) { 8 uimsbf  Information_location_byte     }   }   CRC_32 32 rpchof }

The field, table_id, can be an 8-bit unsigned integer having the value0xBD, identifying the demo private table section.

The field, section_syntax_indicator can be a 1-bit field set to ‘1’ toindicate that this table follows the generic section syntax for tables.

The field, private_indicator, can be a 1-bit field set to ‘1’ toindicate that this is a private table.

The field, section_length, can be a 12-bit unsigned integer containingthe number of bytes following this field to the end of the section. Thisfield should not exceed 4093 bytes.

The field, table_id_extension, can be a 16-bit unsigned integer havingthe value ‘0x0000’, identifying the demo mapping table section.

The field, version_number, can be a 5-bit field containing the versionnumber of this table. The version_number should be incremented by 1modulo 32 when a change in the information carried within the demomapping table occurs. This number should change whenever a table isremoved or added from the set of private data tables being supplied. Theversion number can also increment when a private data table's versionnumber changes.

The field, current_next_indicator, can be a 1-bit field set to ‘1’ toindicate that this is the current valid demo mapping table.

The field, section_number, can be an 8-bit unsigned integer providingthe number of the section. The section_number of the first section in ademo mapping table should be 0x00. The section_number should beincremented by 1 with each additional section in this table.

The field, last_section_number, can be an 8-bit unsigned integerproviding the number of the last section (that is, the section with thehighest section_number) of the table of which this section is a part.

The field, mappings_defined, can be a 16-bit unsigned integer providingthe total number of mapping definitions within this section. A mappingdefinition includes the referenced table extension ID, the referencedtable version number, and a textual string that may be used to referencethe table.

The field, referenced_table_id_extension, can be a 16-bit unsignedinteger defining the extended table ID of the table to be associatedwith the included URL text information. The associated table can containa single file as described in the demo_private_table definition below.

The field, referenced_table_version_number, can be a 5-bit unsignedinteger corresponding to the current version of the associateddemo_private_table. The mapping table should be updated whenever a fileis changed in which case the associated table version should change.

The field, information_location_length, can be an 8-bit unsignedspecifying the total number of bytes in the following informationlocation text. The bytes included in this loop can match precisely thebytes contained in the extended information descriptors as describedabove.

The field, information_location_byte, can be an 8-bit ASCII character.

The field, CRC_(—)32, can be a 32-bit unsigned integer containing theCRC value for this particular table section. The CRC calculation isspecified in the MPEG2 standard, more particularly Annex A, ISO/IEC13818-1.

The following is a variation of the dMT example described above, thisvariation being referred to as the demo Private Table (dPT). Table 12depicts the dPT. Each dPT can contain a single file included as multiplesections. Tables can be differentiated using the table_id_extension inthe section header.

TABLE 12 Bit Stream Syntax for the demo Private Table (dPT) Syntax BitsFormat demo_private_table_section ( ) {   table_id 8 0xBD  section_syntax_indicator 1 ‘1’   private_indicator 1 ‘1’   reserved 2‘11’   section_length 12 uimsbf   table_id_extension 16 uimsbf  reserved 2 ‘11’   version_number 5 uimsbf   current_next_indicator 1‘1’   section_number 8 uimsbf   last_section_number 8 uimsbf   for(j=0;j<section_length−9;j++) {     private_data_byte 8 bslbf   }  CRC_32 32 rpchof }

The fields, table_id, section_syntax_indicator, private_indicator,section_length, table_id_extension, version_number,current_next_indicator, section_number, and last_section_number havebeen described above.

The field, private_data_byte, can be an 8-bit field indicating privatedata that can be concatenated into a complete file at the receiver. Thefile can be considered as a byte stream with section_number 0x00containing the first byte of the stream while last_section_number cancontain the final byte. A single data file can be contained in a singletable. Note that data files can have a maximum size of 256(sections)*4084=1,045,504 bytes=1021 KB=0.9971 MB.

The field, CRC_(—)32, has been described above.

Though especially suited to ATSC compliant DTV technology, the inventionalternatively is applicable to DTV technologies.

The invention being thus described, it will be obvious that the same maybe varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art are intendedto be included within the scope of the following claims.

What is claimed:
 1. A digital television (DTV) transmitter to transmitdigital broadcast data, the DTV transmitter comprising: a Program andSystem Information Protocol (PSIP) generator that generates a PSIP tablefor transmitting in a DTV stream; a transmitter that transmits the DTVstream including the PSIP table to a DTV receiver, the PSIP tablecontaining a virtual channel table (VCT) and an event information table(EIT), the EIT carrying a program schedule for a virtual channel, theEIT including a genre descriptor, the genre descriptor comprising: adescriptor tag field identifying the descriptor as a genre descriptor; adescriptor length field, which is an 8-bit unsigned integer, specifyinga length, in bytes, of fields which immediately follow the descriptorlength field to an end of the genre descriptor, wherein the fieldsinclude: a category selection code, the category selection code being anattribute code value for an associated event in the DTV stream, theattribute code value specifying a basic genre or category type or detailattribute for the associated event in the DTV stream, and the attributecode value matching a value for the basic genre or category type ordetail attribute in a categorical genre code assignments table definedin Advanced Television Standards Committee (ATSC) A/65 standard; andwherein the genre descriptor accommodates a plural attribute code valuessuch that the transmitter transmits the plural attribute code valuessequentially without intervention, and each attribute code value isdefined in the categorical genre code assignments table that is orderedfrom basic genre or category type to detail attribute, and the genredescriptor references entries in the categorical genre code assignmentstable, and when a plurality of attribute code values are included in thegenre descriptor, the basic genre or category type or the detailattribute code values are specified by 8-bit unsigned integer and atleast one attribute code value is specifying a basic genre, and whereinthe EIT covers a three hour period and the VCT includes a major channelnumber field and a minor channel number field.
 2. The DTV transmitter ofclaim 1, wherein the basic genre or category type attribute comprises atleast one of education, entertainment, movie, news, religion, andsports.